东汶河流域第四系地质及河成地貌特征

THE FLUVIAL LANDFORM AND GEOLOGICAL CHARACTER OF QUATERNARY PERIOD IN THE DONGWEN RIVER VALLEY

东汶河流域河成第四系主要有：下更新统洪冲积粘土砂砾层，其中含金刚石，组成Ⅱ阶地；中更新统被剥蚀作用改造的冲积层，它的主要成分是下更新统沉积层被剥蚀改造后的残留物，该层金刚石含量相对较富；上更新统冲积层组成Ⅰ阶地，上叠在Ⅱ阶地之上。故东汶河流域的阶地是上叠型。

The fluvial quaternary system of the Dongwen River valley consists mainly of:(1)proluvial-alluvial clayey-sandgravel beds of the lower pleistocere series, which containsdiamond and constitutes terrace Ⅱ;(2) the alluvium of the middle pleistoccere reformed bydenudation , of which the main constituents are the residuals of the lower pleistocere sedimentsreformed after its denudation and which contains relatively high amount of diamond;(3)thealluvium of the uppet pleistocere forming terrace Ⅰ which piles up on the top of terraceⅡ.Therefore,the terraces in the Dongwen River valley belongs to the upper-overlapping type.